Filter Element Assembly

ABSTRACT

A filter element assembly (10) is disclosed comprising: a filter element (12) for location in a housing (4) of a filter (2), comprising a wall (16) of a filtration medium which defines a hollow space (18), for a gas stream to flow from the space through the wall, the filtration medium including a filtration layer (20), and a drainage layer (22) located outside the filtration layer, first (24) and second (26) end caps at opposite ends of the wall, one including a port (28) for a gas stream which communicates with the space; and a drainage promoter (14) comprising a fin (46) which can be fitted to the filter element so that it extends along the filter element substantially an entire distance between the first and second end caps, the fin compressing the drainage layer along its length to promote drainage of liquid which has collected in the drainage layer.

TECHNICAL FIELD

This invention relates to a filter element assembly for removingmaterial that is entrained in a gas stream. The invention also relatesto a drainage promoter for a filter element, and a filter element.

BACKGROUND

Filtration of gas in a compressed gas system is generally required sothat the gas is sufficiently clean for a subsequent application or tominimise adverse effects of impurities on components of the system. Forexample, removal of compressor oil can be required to minimise chemicalcontamination and accumulation on valves which might lead to malfunctionof the valves.

There are many known filter elements for use in a filter assembly in gassystems. Such filter elements generally comprise a cylindricalfiltration layer or “coalescing layer” and a cylindricalanti-re-entrainment barrier or “drainage layer” surrounding thefiltration layer on the outside of the filter element. The filterelements typically also comprise an end cap having a trough in which thecoalescing and drainage layers are retained.

A gas stream enters the tubular filter element through an inlet port andflows through the cylindrical walls of the filter element, generallyradially outward from the inside of the filter element to the outside.When the assembly is used to collect liquid droplets in the gas stream(for example which is carried in the stream as an aerosol), thefiltration/coalescing layer will cause liquid droplets to coalesce forcollection. The coalesced liquid will be carried by the flow of gas tothe drainage layer where the liquid can collect. The drainage layer isconfigured to ensure that re-entry of the liquid into the gas stream isminimised. In use, the liquid will sink to the bottom of the drainagelayer, from which it can drain into a reservoir where it can collectprior to disposal. If the liquid does not drain from the drainage layerinto the reservoir at least as quickly as liquid is supplied to thedrainage layer, the liquid can tend to collect at the base of thedrainage layer, where it forms a ‘wet band’ in which the material of thedrainage layer is saturated with the liquid.

After prolonged use of the filter element, the depth of the wet band canincrease to the extent that gas flowing through the element wall willpass through the wet band. This can increase the resistance to flow ofgas through the filter element, and therefore give rise to an increasein pressure drop across the filter element. This can result in increasedoperating costs. Furthermore, gas flowing through or near a saturatedpart of the drainage layer can draw droplets of liquid from the drainagelayer into the gas flow, thereby re-contaminating the gas as it isdischarged from the filter element. It can therefore be seen thatsignificant accumulation of liquid in a wet band can reduce theoperating efficiency of the filter element. When the operatingefficiency is significantly reduced, the filter element in the filterassembly must be replaced, giving rise to expense and possibly also arequirement for the system in which the assembly is used to be shutdown.

Filter elements can be arranged so that they are positioned verticallyor horizontally when in use. Traditionally, horizontally placedcoalescing filter elements have a standard circular outer drainagelayer, or a drainage layer with an elongate tab that is made from thesame material as the drainage layer and positioned at the bottom of theelement when it is in its deployed position (i.e., at thecircumferentially bottom position in a horizontally deployed filterelement having a cylindrical shape, viewing along the element).

Reduction of a wet band which can form during use of a filter elementwould allow more area of the un-wetted filtration material to be used,which would improve the performance of the filter element.

SUMMARY

In a first aspect of the present disclosure, there is provided a filterelement assembly comprising:

-   -   a. a filter element for location in a housing of a filter,        comprising a wall of a filtration medium which defines a hollow        space, for a gas stream to flow from the space through the wall        to be filtered, the filtration medium including a filtration        layer, and a drainage layer located outside the filtration layer        in which liquid separated from the gas stream can collect, and        first and second end caps at opposite ends of the wall, one of        the end caps including a port for a gas stream which        communicates with the space within the wall; and    -   b. a drainage promoter comprising a fin which can be        fitted/configured to be connected to the filter element so that        it extends along the filter element substantially an entire        distance between the first and second end caps, the fin        compressing the drainage layer along its length to promote        drainage of liquid which has collected in the drainage layer.

The filter element and the drainage promoter may be capable of beingconnected to one another, or configured to be connected, so that thefilter element and the drainage promoter can be manipulated by a user asa unitary component for positioning in a housing of a filter.

The filter element may be adapted to be disposed, in use, in ahorizontal position or orientation. The drainage promoter fin may thenbe located at a position around a perimeter of the filter element, whichis disposed lowermost, in use. Where the filter element is generallycircular in shape in cross-section (i.e., a generally cylindricallyshaped hollow filter element), the position may be a bottom-mostposition around a circumference of the element, viewing in a directionalong a length of the element in its use position.

The drainage promoter fin may compress the drainage layer of the filterelement, which may break the surface tension of the drainage layermaterial and promote quicker, more efficient drainage of liquid from thedrainage layer. An enhanced drainage effect may therefore be providedover conventional horizontally oriented filter elements, as well as oversuch filter elements comprising a drainage layer including an elongatetab formed of the drainage layer material itself. It may also simplifyconstruction of the filter element, in particular its drainage layer, incontrast to drainage layers comprising such a tab. Further, and in atleast some disclosed embodiments, the drainage promoter fin may becapable of being fitted to a standard filter element, without requiringmodification to the structure of the element.

The fin may be elongate and may have first and second ends (which may beaxial ends). The fin may comprise a base extending along a length of thefin between the ends. The fin may comprise a tip opposite the base andextending along the length of the fin. The tip may define a free edge ofthe fin. A length dimension of the fin may be greater than a heightdimension, the height measured from the base to the tip. The fin maycomprise a longitudinal axis extending along a length of the fin betweenits ends. The base may press into the drainage layer during use. The tipmay be spaced away from the base and may define a discharge locationfrom which liquid flowing from the drainage layer can be discharged fromthe fin. The fin may have a tapered shape in cross-section, whichsection may be taken transverse (suitably perpendicular) to alongitudinal axis of the fin. This may help to promote the flow ofliquid along the fin, for subsequent discharge. The fin may taper in adirection from its base towards its tip. A cross-sectional width of thefin (taken perpendicular to the longitudinal axis) may decrease in adirection towards its tip. The fin may have a height, which may bemeasured in a direction from the base to the tip. The height may besubstantially constant along a length of the fin. The height may varyalong a length of the fin, for example the fin (in particular its base)may be curved and may be generally convex.

The fin may be connectable to at least one of the first and second endcaps, so that it can be secured to the filter element. The fin may beconnectable to both end caps. The fin may extend from one end cap to theother end cap. The fin may be releasably connectable to at least one ofthe end caps, optionally to both end caps. Providing a releasableconnection may allow the drainage promoter fin to be fitted to thefilter element following assembly of the filter element, and/or mayallow the fin to be used with a further filter element, if the elementshould become clogged during use and requires replacement.

The fin may comprise at least one connection (or engaging) feature forengaging the filter element, to connect the fin to the element. Theconnection feature may engage an end cap of the filter element. The finmay comprise a first connection feature for engaging one of the endcaps, and a second connection feature for engaging the other one of theend caps. The first and second connection features may be spaced apartalong a length of the fin. The fin may comprise a first axial end and asecond axial end, and the first and second connection features may beprovided on, at or near the respective first and second axial ends.

The filter element may comprise at least one connection (or engaging)feature, which may cooperate with the connection feature on the fin, forconnecting the fin to the element. At least one of the end caps maycomprise the connection feature. The first end cap may comprise a firstconnection feature and the second end cap may comprise a secondconnection feature. The first and second end cap connection features mayeach be configured to cooperate with the respective first and secondconnection features of the fin, to connect the fin to the element.

The connection feature of the fin may be a male connection feature andthe connection feature of the filter element may be a correspondingfemale connection feature. The connection feature of the fin may be afemale connection feature and the connection feature of the filterelement may be a corresponding male connection feature. Where the fincomprises first and second connection features, they may each be a maleconnection feature, each a female connection feature, or a mixture ofmale and female connection features may be provided. The first andsecond connection features of the filter element may therefore each be afemale connection feature, each a male connection feature, or a mixtureof male and female connection features may be provided, as appropriate.

The female connection feature may define an opening or entrance which isshaped to receive the male connection feature. The male connectionfeature may be a protrusion or projection, such as a pin, boss, shaft,finger, rib or the like. The female connection feature may be a recess,socket, bore, channel, passage or the like.

The filter element assembly may comprise a pivoting connection betweenthe fin and the filter element. The pivoting connection may be definedby the connection features of the fin and the filter element. One of thefin and the filter element may define a connection feature in the formof a pivot pin or shaft, and the other one of the fin and the filterelement may define a pivot mount or socket shaped to receive the pivotpin, so that the fin can pivot relative to the filter element.

The pivot pin and pivot mount may be aligned with, or along, alongitudinal axis of the fin, so that the fin can pivot about thelongitudinal axis. The fin may be pivotable between a folded (orinstallation) position and a deployed (or use) position. The fin may bepivotable generally about or near to its base. When the fin is in thefolded position, a tip of the fin may be disposed closer to an outersurface of the drainage layer than when the fin is in its deployedposition. A flank of the fin may be disposed proximate the outer surfaceof the drainage layer when the fin is in its folded position. Theability of the fin to fold in this way may facilitate fitting of thefilter element assembly in the filter housing, for example if access tothe housing is restricted. The fin may comprise a pivot pin, or a pivotmount at each of its ends, configured to engage a corresponding pivotmount or pivot pin of the filter element. The fin may comprise a pivotpin at both ends, a pivot mount at both ends, or a pin at one end and amount at the other.

The pivot pin may be disposed transverse (e.g., perpendicular) to thelongitudinal axis of the fin. A pair of pivot pin portions may beprovided, and axes of the pin portions may be aligned. A first pivot pinportion may extend in a first lateral direction away from the fin, and asecond pivot pin portion may extend in a second lateral direction awayfrom the fin. The lateral directions may be transverse to thelongitudinal axis of the pin and are suitably perpendicular to it. Thepivot pin and the pivot mount/socket may be disposed on a pivot axiswhich is transverse to the longitudinal axis of the fin, suitablyperpendicular to it, when the fin is connected to the filter element.The arrangement may be reversed, with pin portions provided by thefilter element (suitably an end cap) and a mount on the fin.

The fin may be pivotable about the pivot axis between a disconnectedposition in which the fin can be disconnected from the filter element,and a connected position in which the fin is connected to the filterelement. In the disconnected position, a longitudinal axis of the finmay be disposed transverse to a longitudinal axis of the filter element.In the connected position, a longitudinal axis of the fin may bedisposed substantially parallel to a longitudinal axis of the filterelement.

The fin and the filter element may define respective latch features,which may cooperate to provide a latching engagement between the fin andthe element. The latch feature on the fin may be spaced along a lengthof the fin from the pivot pin or pivot mount. The latch feature on thefilter element may be provided on one of the end caps. One of the latchfeatures provided by the fin and the filter element may be a resilientlydeformable element such as a latch arm, finger, catch or the like, andthe other latch feature may be a recess, bore or the like, or an edgesurface or face.

The filter element assembly may comprise a sliding connection betweenthe fin and the filter element. The sliding connection may be defined bythe connection features of the fin and the filter element. The fin maybe translatable relative to the filter element between a disconnectedposition in which it is not connected to the filter element, and aconnected position in which it is connected to the filter element. Oneof the fin and the filter element may define a connection feature in theform of a protrusion or projection, which may form a key, and which maybe a tab, finger or the like. The other one of the fin and the filterelement may define a connection feature shaped to receive the protrusionin a sliding fit, may form a keyway, and may be a channel, recess, guideor the like. The key and keyway may have to be aligned for engagement ofthe connection features. The sliding connection may comprise a restraintwhich may serve to resist further translation of the fin relative to thefilter element (in at least one direction), once the fin has beentranslated a sufficient distance relative to the filter element andadopted its connected position. The restraint may be a shoulder, whichmay be provided or defined by the fin and/or the filter element, inparticular by their connection features.

The first end cap may comprise a first connection feature for engaging acorresponding first connection feature on the fin. The second end capmay comprise a second connection feature for engaging a correspondingsecond connection feature on the fin. The respective first connectionfeatures of the filter element and the fin, and the respective secondconnection features of the filter element and the fin, may require to bealigned in order for the fin to be connected to the element. Theconnection features of the filter element may be aligned along an axisextending along the filter element substantially parallel to itslongitudinal axis. At least one of the end caps may comprise a pluralityof connection features, which may be spaced around a perimeter of theend cap. This may be advantageous during assembly of the filter element,facilitating rotational alignment of the end cap connection features, sothat the fin can subsequently be fitted to the element.

The fin may compress the drainage layer along a majority, or all, of alength of the drainage layer defined or exposed between the first andsecond end caps of the filter element. This may serve to promote maximumdischarge of liquid from the drainage layer, along a length of thedrainage layer disposed between the end caps, during use. The fin may becaptured between the end caps. The fin may extend at least partly overone or both of the first and second end caps. When the fin is fitted tothe filter element, a small gap may be provided between one or both ofthe end caps and a facing surface of the fin. The facing surface may bein the region of and/or may define the base. The small gap mayfacilitate sliding connection of the fin to the filter element.

The fin may be configured so that it is connected to the filter elementin a press-fit, suitably between the end caps. The fin may beresiliently deformable so that it can be press-fitted to the filterelement.

The drainage promoter may comprise at least one drainage element, suchas a finger, rib, arm or the like, the drainage element being coupled tothe fin and extending in a direction away from the fin. The drainageelement may be resilient and/or elastically deformable. The drainageelement may extend in a direction around an outer surface of thedrainage layer. The drainage element may compress the drainage layeralong at least part of its length, which may serve to further promotethe drainage of liquid from the drainage layer. The drainage element mayextend part way around a perimeter of the outer surface. The drainageelement may be disposed transverse to a longitudinal axis of the fin andmay be disposed substantially perpendicular to the fin axis. Thedrainage element may be curved and may have an inner surface with acurvature which substantially matches a curvature of the outer surfaceof the drainage layer (e.g., for a circular section filter element).

The at least one drainage element may have a base at which it is coupledto the fin and may extend away from the base to a tip, which may definea free end. The at least one drainage element may taper in a directionfrom the base towards the tip. A width of the at least one drainageelement (considered in an axial direction relative to the filterelement), and/or a depth (considered in a radial direction relative tothe filter element) may reduce in a direction towards the tip. This mayhelp to promote the flow of liquid along the drainage element and on tothe fin, for subsequent discharge.

At least one first drainage element may extend from the fin, optionallyaround the outer surface of the drainage layer in a first directionaround the perimeter of the filter element. At least one second drainageelement may extend from the fin, optionally around the outer surface ofthe drainage layer in a second direction around the perimeter of thefilter element. The second direction may be opposite to the firstdirection. The first and second drainage elements may extend fromrespective first and second flanks of the fin. The drainage elementsextending in the different directions may be disposed at common axialpositions along a length of the fin or may be axially staggered.

The first and second drainage elements, extending in the differentdirections, may be configured to together impart a clamping force on thefilter element, for connecting the drainage promoter to the element.This may be facilitated by inherent resiliency, or elasticdeformability, of the drainage elements. The drainage elements may beconsidered to form connection features, for connecting the fin to thefilter element, and may alternatively be referred to as connectionfeatures. The drainage elements may each extend around the perimeter ofthe filter element to an over-centre position, relative to a centralaxis of the filter element. This may provide the clamping force. Thefirst and second drainage elements may therefore together encompass morethan half of a circumference of a circular filter element.

The first and second drainage elements may together describe a generallycylindrical passage or opening between their inner surfaces, whichpassage may be shaped to receive the filter element and may have acentral axis. The drainage elements may each extend to an over-centreposition, relative to the central axis. A space may be defined betweenthe free end of the first drainage element and the free end of theaxially adjacent second drainage element. A dimension of the space,measured in a direction perpendicular to the longitudinal axis of thefilter element, may be smaller than a diameter (or width as appropriate)of the filter element. This may provide the clamping force.

The drainage promoter may be connectable to the filter element at alocation between the first and second end caps. The drainage promotermay be connectable to the drainage layer of the filter element. Thedrainage promoter may comprise at least one connecting component whichcan engage the drainage layer, to connect the fin to the filter element.The connecting component may be a strap or tie, which may extend fromthe fin and around at least part of a perimeter of the drainage layer.The strap or tie may be provided separately and may be connectable tothe fin to secure it to the filter element, for example by passingthrough a locating aperture in the fin and around the discharge layer.In a variation, a strap may be connectable to an end cap, by passingaround a perimeter of the cap.

The strap may comprise a first strap portion extending in a firstdirection away from the fin and around part of a perimeter of thedrainage layer. The strap may comprise a second strap portion extendingin a second direction away from the fin and around part of a perimeterof the drainage layer, which second direction may be opposite to thefirst direction. The first and second strap portions may be adapted tobe coupled together to connect the fin to the filter element. The firstand second strap portions may comprise respective connection featuresfor coupling them together. One of the strap portions may comprise amale connection feature such as a button or stud, and the other one ofthe strap portions may comprise a female connection feature such as anaperture, the aperture receiving the button in a press fit. The strapportions may carry other connection features, such as zip-tiestructures. The first and second strap portions may together encirclethe drainage layer when coupled together.

The strap may extend from the fin around substantially the entireperimeter of the drainage layer. The strap may have a free end which isadapted to be coupled to the fin so that the strap encircles thedrainage layer, to connect the fin to the filter element.

A first strap may be provided at a first axial location along a lengthof the fin, and a second strap may be provided which is at a secondaxial location along the length of the fin. The provision of two strapsmay provide a secure connection of the fin to the filter element.Further such straps may be provided if desired, which may depend onfactors including dimensions of the filter element.

The drainage promoter may be connectable to the drainage layer of thefilter element via connection features of the type described as drainageelements above. The connection features may then optionally have adrainage function as described. The drainage promoter may comprise afirst part defining a first part of the fin and at least onedrainage/connection element, and a second part defining a second part ofthe fin and at least one drainage/connection element. The first andsecond fin parts may be adapted to be coupled together to define thedrainage promoter. This may facilitate fitting of the drainage promoterto the filter element, in particular where it is fitted to the drainagelayer.

Reference is made in this document to a fin which compresses a drainagelayer of a filter element along its length. It will be understood thatthe fin will not necessarily compress the drainage layer along itsentire length, and thus that a compressive effect of the fin on thedrainage layer may occur along only a part of the length of the fin. Thefin may overlap the drainage layer along a part of its length, and acompressive effect may be provided along the part which overlaps thedrainage layer, and optionally the entire part which overlaps.

In a second aspect of the present disclosure, there is provided adrainage promoter which can be connected to a filter element, thedrainage promoter comprising:

-   -   a. at least one fin which can be fitted to the filter element so        that it extends along the filter element substantially an entire        distance between first and second end caps of the filter        element, to compress a drainage layer of the filter element        along its length and promote drainage of liquid which has        collected in the drainage layer;    -   b. in which the fin comprises a first connection feature for        engaging the first end cap of the filter element, and a second        connection feature for engaging the second end cap of the filter        element, for connecting the fin to the filter element.

The fin may be releasably connectable to the end caps. The first andsecond connection features may be adapted to cooperate withcorresponding connection features on the end caps. The connectionfeatures may be male connection features adapted to cooperate withcorresponding female connection features on the end caps. The connectionfeatures may be female connection features adapted to cooperate withcorresponding male connection features on the end caps. One of theconnection features may be a male feature and the other a femalefeature.

One of the first and second connection features may be a pivotingconnection feature, providing a pivoting connection between the fin andthe end cap. This may facilitate pivoting movement of the fin relativeto the filter element, between a position where an axis of the fin istransverse to a longitudinal axis of the filter element, and a positionwhere the fin axis is substantially parallel to the filter element axis.At least one of the first and second connection features may define alatch feature, which may provide a latching engagement between the finand the end cap.

The first and second connection features may both be pivoting connectionfeatures, providing a pivoting connection between the fin and the endcap. This may facilitate pivoting movement of the fin relative to thefilter element, about a pivot axis defined by or parallel to alongitudinal axis of the fin. In this way, the fin may be pivotedbetween a folded (or installation) position and a deployed (or use)position.

The first and second connection features may be adapted to provide asliding connection between the fin and the end caps.

In a third aspect of the present disclosure, there is provided adrainage promoter which can be connected to a filter element, thedrainage promoter comprising:

-   -   a. at least one fin which can be fitted to the filter element so        that it extends along the filter element substantially an entire        distance between the first and second end caps, to compress a        drainage layer of the filter element along its length and        promote drainage of liquid which has collected in the drainage        layer; and    -   b. at least one connecting component which can engage the        drainage layer to connect the fin to the filter element.

The drainage promoter may be connectable to the filter element at alocation between the first and second end caps.

The connecting component may be a strap or tie which extends from thefin and around at least part of a perimeter of the drainage layer.

The strap may comprise a first strap portion extending in a firstdirection away from the fin and around part of a perimeter of thedrainage layer. The strap may comprise a second strap portion extendingin a second direction away from the fin and around part of a perimeterof the drainage layer, which second direction may be opposite to thefirst direction. The first and second strap portions may be adapted tobe coupled together to connect the fin to the filter element.

The strap may extend from the fin around substantially the entireperimeter of the drainage layer and may have a free end which is adaptedto be coupled to the fin so that the strap can encircle the drainagelayer, and connect the fin to the filter element.

The connecting component may take the form of a resilient or elasticallydeformable rib, finger or the like, which may be coupled to the fin andextend in a direction away from the fin. The connecting component mayextend, in use, in a direction around an outer surface of the drainagelayer. The connecting component may be disposed transverse to alongitudinal axis of the fin and may be disposed substantiallyperpendicular to the fin axis.

The connecting component may be curved and may have an inner surfacewith a curvature which substantially matches a curvature of an outersurface of the filter element drainage layer (for a circular sectionfilter element).

At least one first connecting component may extend from the fin in afirst direction. At least one second connecting component may extendfrom the fin in a second direction, which may be opposite to the firstdirection. The first and second connecting components extending in thedifferent directions may be configured to together impart a clampingforce on the drainage layer of the filter element, for connecting thedrainage promoter to the element. The connecting components may describea generally cylindrical passage or space between inner surfaces of thecomponents, which passage may be shaped to receive the filter element,the passage having a central axis. The connecting components may eachextend to an over-centre position, relative to the central axis. Thismay provide the clamping force.

In a fourth aspect of the present disclosure, there is provided adrainage promoter which can be connected to a filter element, thedrainage promoter comprising:

-   -   a. at least one fin which can be fitted to the filter element so        that it extends along the filter element substantially an entire        distance between the first and second end caps, to compress a        drainage layer of the filter element along its length and        promote drainage of liquid which has collected in the drainage        layer, the fin having first and second axial ends and a        longitudinal axis extending along the fin between its axial        ends; and    -   b. at least one drainage element coupled to the fin and        extending in a direction away from the fin, transverse to its        longitudinal axis.

The at least one drainage element may extend, in use, in a directionaround an outer surface of the drainage layer. The at least one drainageelement may compress the drainage layer along at least part of itslength, which may serve to further promote the drainage of liquid fromthe drainage layer. The at least one drainage element may extend partway around a perimeter of the outer surface. The at least one drainageelement may be disposed substantially perpendicular to the fin axis.

The drainage promoters of the second to fourth aspects may beconnectable to the filter element so that, in use, the filter elementand the drainage promoter can be manipulated by a user as a unitarycomponent for positioning in a housing of a filter.

The drainage promoters defined in the second to fourth aspects,including the fins forming part of the drainage promoters, may have anyof the further features of the drainage promoters defined elsewhere inthis document, particularly in or with reference to the filter elementassembly of the first aspect.

In a fifth aspect of the present disclosure, there is provided a methodof improving drainage of liquid from a drainage layer of an existingfilter element, the method comprising fitting a drainage promoteraccording to the third or fourth aspect of the present disclosure to thedrainage layer of the filter element.

Further features of the method may be derived from the text set outelsewhere in this document.

In further aspects of the present disclosure, filter element assembliesmay be provided comprising a filter element and a drainage promoteraccording to any one of the second, third or fourth aspects.

The filter element may be for location in a housing of a filter,comprising a wall of a filtration medium which defines a hollow space,for a gas stream to flow from the space through the wall to be filtered,the filtration medium including a filtration layer, and a drainage layerlocated outside the filtration layer in which liquid separated from thegas stream can collect, and first and second end caps at opposite endsof the wall, one of the end caps including a port for a gas stream whichcommunicates with the space within the wall.

In a further aspect of the present disclosure, there is provided afilter element assembly comprising:

-   -   a. a filter element for location in a housing of a filter,        comprising a wall of a filtration medium which defines a hollow        space, for a gas stream to flow from the space through the wall        to be filtered, the filtration medium including a filtration        layer, and a drainage layer located outside the filtration layer        in which liquid separated from the gas stream can collect, and        first and second end caps at opposite ends of the wall, one of        the end caps including a port for a gas stream which        communicates with the space within the wall; and    -   b. a drainage promoter connected to the filter element so that        it extends along the filter element substantially an entire        distance between the first and second end caps, the fin        compressing the drainage layer along its length to promote        drainage of liquid which has collected in the drainage layer.

The filter element and the drainage promoter may be configured to bemanipulated by a user as a unitary component for positioning in ahousing of a filter.

The filter element and/or the drainage promoter may have any of thefurther features defined elsewhere in this document, particularly in orwith reference to the first aspect.

In a further aspect of the present disclosure, there is provided afilter element for location in a housing of a filter, the filter elementcomprising:

-   -   a. a wall of a filtration medium which defines a hollow space,        for a gas stream to flow from the space through the wall to be        filtered, the filtration medium including a filtration layer,        and a drainage layer located outside the filtration layer in        which liquid separated from the gas stream can collect;    -   b. first and second end caps at opposite ends of the wall, one        of the end caps including a port for a gas stream which        communicates with the space within the wall; and    -   c. at least one connection feature configured to cooperate with        a connection feature on a drainage promotor fin, for connecting        the filter element to the drainage promotor fin.

The at least one connection feature may be provided on one of the firstand second end caps. A connection feature may be provided on both of theend caps. The first end cap may comprise a first connection feature andthe second end cap may comprise a second connection feature. The firstand second end cap connection features may each be configured tocooperate with respective first and second connection features of thedrainage promoter fin, to connect the fin to the element.

The filter element may have any of the further features definedelsewhere in this document, particularly in or with reference to thefirst aspect. In particular, the at least one connection feature of thefilter element may have any of the further features defined in, or inrelation to, the first aspect.

Filter element assemblies, drainage promoters, filter elements and amethod of improving drainage of liquid from a drainage layer of anexisting filter element are defined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a front view of a filter element assembly in accordance withan embodiment of the present disclosure;

FIG. 1A is a longitudinal cross-sectional view of a filter comprisingthe filter element assembly of FIG. 1 , drawn to a smaller scale;

FIG. 2 is an end view of the filter element assembly shown in FIG. 1 ,taken in the direction of the arrow A in FIG. 1 ;

FIG. 3 is an end view of the filter element assembly shown in FIG. 1 ,taken in the direction of the arrow B in FIG. 1 ;

FIG. 4 is a longitudinal cross-sectional view of the filter elementassembly shown in FIG. 1 ;

FIG. 5 is a front view of a drainage promoter forming part of the filterelement assembly shown in FIG. 1 ;

FIG. 6 is an end view of a drainage promoter forming part of the filterelement assembly shown in FIG. 1 ;

FIG. 7 is a perspective view of a drainage promoter forming part of thefilter element assembly shown in FIG. 1

FIG. 8 is a perspective view of the filter element assembly shown inFIG. 1 , drawn to a smaller scale;

FIG. 9 is an end view of the filter element assembly, drawn to thesmaller scale of FIG. 8 , and showing fitting of the drainage promoterto a filter element of the assembly;

FIG. 10 is a perspective view of the filter element assembly, drawn tothe smaller scale of FIG. 8 , and showing fitting of the drainagepromoter to a filter element of the assembly;

FIG. 11 is a front view of a filter element assembly in accordance withanother embodiment of the present disclosure;

FIG. 12 is an end view of the filter element assembly shown in FIG. 11 ,taken in the direction of the arrow A in FIG. 11 ;

FIG. 13 is an end view of the filter element assembly shown in FIG. 11 ,taken in the direction of the arrow B in FIG. 11 ;

FIG. 14 is a perspective view of the filter element assembly shown inFIG. 11 , drawn to a smaller scale;

FIG. 15 is a longitudinal cross-sectional view of the filter elementassembly shown in FIG. 11 , drawn to a smaller scale;

FIG. 16 is an end view of the filter element assembly, drawn to thesmaller scale of FIG. 14 , and showing fitting of a drainage promoter toa filter element of the assembly;

FIG. 17 is a front view of the drainage promoter forming part of thefilter element assembly shown in FIG. 11 ;

FIG. 18 is an end view of the drainage promoter forming part of thefilter element assembly shown in FIG. 11 ;

FIG. 19 is a perspective view of the drainage promoter forming part ofthe filter element assembly shown in FIG. 11 ;

FIG. 20 is an enlarged detail view showing connection features of thefilter element and the drainage promoter following connection of thedrainage promoter to the filter element;

FIG. 21 is a further enlarged detail view showing connection features ofthe filter element and the drainage promoter following connection of thedrainage promoter to the filter element;

FIG. 22 is a front view of a filter element assembly in accordance witha further embodiment of the present disclosure;

FIG. 23 is an end view of the filter element assembly shown in FIG. 22 ,taken in the direction of the arrow A in FIG. 22 ;

FIG. 24 is an end view of the filter element assembly shown in FIG. 22 ,taken in the direction of the arrow B in FIG. 22 ;

FIG. 25 is a longitudinal cross-sectional view of the filter elementassembly shown in FIG. 22 ;

FIG. 26 is a perspective view of the filter element assembly shown inFIG. 22 , illustrating a drainage promoter being fitted to a filterelement of the assembly;

FIG. 26A is a side view of the filter element assembly shown in FIG. 22, showing a first step fitting of a drainage promoter to a filterelement of the assembly;

FIG. 26B is a side view of the filter element assembly shown in FIG. 22, showing a second step fitting of a drainage promoter to a filterelement of the assembly;

FIG. 26C is a side view of the filter element assembly shown in FIG. 22, showing a third step fitting of a drainage promoter to a filterelement of the assembly;

FIG. 27 is a side view of the drainage promoter forming part of theassembly of FIG. 22 ;

FIG. 28 is an end view of the drainage promoter forming part of theassembly of FIG. 22 ;

FIG. 29 is a perspective view of the drainage promoter forming part ofthe assembly of FIG. 22 ;

FIG. 30 is a front view of a filter element assembly in accordance witha further embodiment of the present disclosure;

FIG. 31 is a front view of a drainage promoter forming part of thefilter element assembly shown in FIG. 30 ;

FIG. 32 is an end view of a drainage promoter forming part of the filterelement assembly shown in FIG. 30 ;

FIG. 33 is a perspective view of a drainage promoter forming part of thefilter element assembly shown in FIG. 30 ;

FIG. 34 is a front view of a filter element assembly in accordance witha further embodiment of the present disclosure;

FIG. 35 is an end view of the filter element assembly shown in FIG. 34 ,taken in the direction of the arrow A in FIG. 34 ;

FIG. 36 is an end view of the filter element assembly shown in FIG. 34 ,taken in the direction of the arrow B in FIG. 34 ;

FIG. 37 is a perspective view of the filter element assembly shown inFIG. 34 , drawn to a smaller scale;

FIG. 38 is a longitudinal cross-sectional view of the filter elementassembly shown in FIG. 34 , drawn to a smaller scale;

FIG. 39 is a front view of a drainage promoter forming part of thefilter element assembly shown in FIG. 34 , drawn to a smaller scale;

FIG. 40 is an end view of a drainage promoter forming part of the filterelement assembly shown in FIG. 34 , drawn to a smaller scale;

FIG. 41 is a perspective view of a drainage promoter forming part of thefilter element assembly shown in FIG. 34 , drawn to a smaller scale;

FIG. 42A is an end view of the filter element assembly of FIG. 34 ,shown during fitting of the drainage promoter to the filter element;

FIG. 42B is an end view of the drainage promoter forming part of thefilter element assembly of FIG. 34 , showing assembly of the drainagepromoter;

FIG. 43 is a front view of a filter element assembly in accordance witha further embodiment of the present disclosure;

FIG. 44 is an end view of the filter element assembly shown in FIG. 43 ,taken in the direction of the arrow A in FIG. 43 ;

FIG. 45 is an end view of the filter element assembly shown in FIG. 43 ,taken in the direction of the arrow B in FIG. 43 ;

FIG. 46 is a front view of a drainage promoter forming part of thefilter element assembly shown in FIG. 43 , drawn to a smaller scale;

FIG. 47 is an end view of a drainage promoter forming part of the filterelement assembly shown in FIG. 43 , drawn to a smaller scale;

FIG. 48 is a perspective view of a drainage promoter forming part of thefilter element assembly shown in FIG. 43 , drawn to a smaller scale;

FIG. 49 is a front view of the filter element assembly shown in FIG. 43, shown during fitting of the drainage promoter to a filter element ofthe assembly, drawn to a smaller scale;

FIG. 50 is an end view of the filter element assembly shown in FIG. 43 ,shown during fitting of the drainage promoter to a filter element of theassembly, drawn to a smaller scale;

FIG. 51 is a longitudinal cross-sectional view of the filter elementassembly shown in FIG. 43 , drawn to the smaller scale of FIG. 49 andshown following fitting of the drainage promoter to the filter element;and

FIG. 52 is a perspective view of the filter element assembly shown inFIG. 43 , drawn to the smaller scale of FIG. 49 and shown followingfitting of the drainage promoter to the filter element.

DETAILED DESCRIPTION

Turning firstly to FIG. 1 , there is shown a front view of a filterelement assembly in accordance with an embodiment of the presentdisclosure, the filter element assembly indicated generally by referencenumeral 10. The filter element assembly 10 is also shown in the endviews of FIGS. 2 and 3 , taken in the direction of the arrows A and Brespectively in FIG. 1 , and the longitudinal cross-sectional view ofFIG. 4 , which is drawn to a larger scale.

In use, and as is well known in the field of fluid filters, the filterelement assembly 10 is located in a filter 2, as shown in thecross-sectional view of FIG. 1A, drawn to a smaller scale. The filterelement assembly 10 is located within a chamber defined by a housing 4of the filter 2. The housing 4 includes an opening 5 through which thefilter element assembly 10 can be inserted into the housing for locationin the chamber 3. A cover 6 is then coupled to the housing 4, to securethe filter element assembly 10 in the chamber 3 so that fluid to befiltered can be directed through the filter element assembly 10, from afilter head 7. A tie-rod 8 secures the filter element assembly 10 withinthe housing 4. Gas to be filtered enters the filter head 7 through aport 9 and flows into the filter element assembly 10 to be filtered.

The filter element assembly 10 comprises a filter element 12, and adrainage promoter, which is indicated by reference numeral 14. As bestshown in FIG. 4 , the filter element 12 comprises a wall 16 of afiltration medium defining a hollow space 18, for a gas stream to flowfrom the space through the wall to be filtered. The filtration mediumincludes a filtration layer 20, and a drainage layer 22 located outsidethe filtration layer, in which liquid separated from the gas stream cancollect. Filter elements having such filtration and drainage layers arewell known in the field of fluid filters, and persons skilled in the artwill appreciate their general construction and operation during use.Accordingly, the filtration and drainage layers 20 and 22, includingtheir materials and methods of manufacture, will not be described indetail in this document. In general terms however, the filtration anddrainage layers 20 and 22 may have the following features.

The material for the filtration medium in the filtration layer 20 of thefilter element 12 will be selected according to the nature of the gasthat is to be filtered, the nature of the contaminants (liquid droplets,aerosols, solid particles etc.) to be filtered from the gas, thepressure differential across the filter and so on. Such materials areknown, including those used by Parker Domnick Hunter in products whichare available under the trademark OIL-X. Suitable materials include, butare not restricted to, borosilicate and other glass fibres, activatedcarbon minerals, activated silica materials and so on.

The filtration layer 20 can be made from woven fibres. However, as willbe appreciated, the filtration layer can be made from sheets ofnon-woven fibres. For example, a microfibre filtration layer made fromfine organic or inorganic fibres may be employed. A coarser fibre layermay be fitted on the inside of a microfibre filtration layer, which mayprotect a microfibre filtration layer from gross pollution. Thefiltration layer 20 may comprise a layer of a material which has beenfolded so that it is fluted (or pleated). This can increase the surfacearea of the filtration layer 20 through which gas flowing through thefilter element 12 will pass. This can also help to increase the rigidityof the filtration layer 20.

The drainage layer 22 comprises a material that is capable of retainingliquid that has been coalesced by the filtration layer 20 and is carriedto the drainage layer by the gas stream that flows through the drainagelayer. The drainage layer 22 will generally be porous and made from amaterial which encourages flow of coalesced liquid towards the base ofthe filter element 12. Factors affecting the drainage characteristicsmay include pore size and structure, and the material of the drainagelayer 22, including for example the surface energy of liquid which is incontact with the material. Materials suitable for use in the drainagelayer are used in similar products sold by Parker Domnick Hunter underthe trade mark OIL-X. Suitable materials include open-celled foamplastics, felted fabric material, expanded foam materials, woven andnon-woven materials.

The filter element 12 also comprises first and second end caps 24 and 26at opposite ends of the wall 16, the first end cap including a port 28for the gas stream to flow into the filter element from the filter headport 9, the filter port 28 communicating with the space 18 within thewall. In normal use of the filter, the filter element 12 will besubstantially horizontally oriented as shown in FIG. 1A, so that thefirst end cap 24 defines a first lateral end of the filter element, andthe second end cap 26 defines a second lateral end of the filterelement.

Perforated tubular supports 30 and 32, typically of a metal or metalalloy material, are secured to the end caps 24 and 26, and serve forsecuring both the filtration layer 20 and the drainage layer 22 to theend caps and separating the different layers. As is well known in thefield of the invention, this is suitably achieved by ‘potting’ thesupports 30 and 32, and the filtration and drainage layers 20 and 22,within annular channels 34 and 36 defined by the end caps 24 and 26,using an adhesive such as an epoxy-based adhesive.

The filter head comprises a flow conduit 33 which defines the inlet port9 and serves to direct a gas stream entering the filter head into thefilter element 12 through its inlet port 28, so that contaminants in thegas stream can be removed. The filter may have a wide range of uses butmay have a particular use in removing contaminants from a gas streamsuch as a compressed or vacuum gas stream which is to be used in anindustrial application, to remove residual oil from a compressor used topressurise the gas.

The first end cap 22 of the filter element 11 comprises a seal in theform of an O-ring 37 (FIG. 1A), which is mounted in a groove 38 definedin a tubular wall 40 of the end cap defining the port 28. The O-ringseal 37 serves for sealing the filter element 12 relative to the filterhead conduit 33, so that gas entering the head is directed into thefilter element. The gas stream entering the filter element 12 flowsthrough its port 28 generally in a direction along an axis 42 of thefilter element, and into the space 18. The gas stream containing thecontaminants flows from the central space 18 radially outwardly, throughthe wall 16 of the filter element 12, passing through the filtrationlayer 20 and the drainage layer 22. The filtration layer 20 serves forfiltering out contaminants, which as described above may be residual oilentrained in the gas stream. Oil droplets coalesce and enter thedrainage layer 22, building up to form a ‘wet band’ towards a lower partof the drainage layer. The liquid oil in this wet band progressivelydrains from the lower part of the drainage layer 22 into a sump 43 ofthe filter housing 4 and can flow out of the sump via a drain 45.

The ‘clean’ gas stream exiting the drainage layer 22 flows out throughan external surface 44 of the filter element 12 (defined by the drainagelayer 22) and into the chamber 3, before passing to an outlet conduit 47of the filter housing 4. The gas stream exiting the filter 2 flows on toa downstream location.

The filter element assembly 10 of the present disclosure also comprisesthe drainage promoter 14. The drainage promoter 14 is shown separatelyin the front and end views of FIGS. 5 and 6 , and the perspective viewof FIG. 7 . The drainage promoter 14 comprises a fin 46 which can befitted to the filter element 12 so that it extends along the filterelement substantially an entire distance between its first and secondend caps 24 and 26, as can be seen for example in FIGS. 1 and 4 . Thefin 46 acts to compress the drainage layer 22 of the filter element 12along its length, to promote drainage of liquid which has collected inthe drainage layer. In the exemplary use discussed above, this is oilwhich has coalesced from the gas flowing through the filter element 12,in the drainage layer 22. The drainage promoter fin 46 compresses thedrainage layer 22 of the filter element 12, breaking the surface tensionof the drainage layer material and promoting quicker and more deficientdrainage of liquid from it. The filter element 12 and the drainagepromoter 14 are capable of being connected to one another so that thefilter element and the drainage promoter can be manipulated by a user asa unitary component for positioning in the housing 4 of the filter 2.

The fin 46 is elongate, having first and second axial ends 48 and 50.The fin 46 also comprises a base 52 which extends along a length of thefin between its axial ends 48 and 50, and a tip 54 which defines a freeedge of the fin. The tip 54 is disposed opposite the base 52, andsimilarly extends along the length of the fin 46. A length dimension ofthe fin 46 measured between its two ends 48 and 50 is greater than aheight dimension, measured from the base 52 to the tip 54. In theillustrated embodiment, the height dimension is substantially constantalong the length of the fin 46. However, the height may vary along alength of the fin 46, for example the fin (in particular its base 52)may be curved and may be generally convex.

As discussed above, during use, the fin 46 presses into the drainagelayer 22. This is best shown in the cross-sectional view of FIG. 4 , thefin base 52 pressing into the drainage layer 22 to break the surfacetension and promote drainage of liquid. Liquid flowing from the drainagelayer 22 on to the fin 46 flows in a direction from the base 52 towardsthe tip 54, the tip defining a discharge location from which the liquidcan be discharged from the fin into the housing sump 43, as discussedabove. The fin 46 has a tapered shape in cross-section, taken in adirection which is perpendicular to a longitudinal axis 56 of the fin.This tapered shape can be best seen in the end and perspective views ofFIGS. 6 and 7 . Providing the fin 46 with such a tapered shape helps topromote the flow of liquid along the fin to its tip 54, and subsequentdischarge. As can be seen, a cross-sectional width of the fin decreasesin a direction away from its base 52 towards its tip 54. The base 52 hasa generally rounded profile so as to reduce a likelihood of damaging thematerial of the drainage layer 22.

The fin 46 is releasably connectable to the filter element at its firstand second end caps 24 and 26. Releasably connecting the fin 46 to thefilter element 12 allows the drainage promoter to be fitted to thefilter element following assembly of the element. It may also allow thedrainage promoter 14 to be used with a further filter element, forexample if the existing filter element in the filter 2 becomes cloggedand requires replacement.

In the illustrated embodiment, the fin 46 comprises first and secondconnection features 58 and 60 at its first and second axial ends 48 and50, which serve for connecting the fin to the filter element 12. Thefirst and second connection features 58 and 60 each take the form of amale feature, in particular a protrusion or projection defining a pivotpin, as best shown in FIG. 7 . The pivot pins 58 and 60 are generallycylindrically shaped and have respective rounded heads 59 and 61. Thefilter element 12 comprises corresponding first and second connectionfeatures 62 and 64, which cooperate respectively with the first andsecond connection features 58 and 60 of the fin 46. In the illustratedembodiment, the first and second connection features 62 and 64 of thefilter element 12 are provided respectively on the first and second endcaps 24 and 26 and are female connection features in the form of a pivotmount or socket which is shaped to receive the pins 58 and 60 of the fin46. To this end, the sockets are typically circular in shape, defining acylindrical space which can receive the cylindrical pins 58 and 60.

The pins 58 and 60, and the sockets 62 and 64, together provide apivoting connection between the fin 46 and the filter element 12. Thepins 58 and 60 can rotate within the sockets 62 and 64, so that the fin46 can be pivoted between a folded or installation position, and adeployed or used position. Reference is made here to FIGS. 8, 9 and 10which are a perspective view of the filter element 12, an end view takenin the direction of the arrow B in FIG. 1 , and a front view similar toFIG. 1 , respectively, all drawn to a smaller scale. The fin 46 is shownin its deployed position in FIG. 8 (as well as FIGS. 1 to 4 ). FIG. 9also shows the fin 46 in its deployed position, as well as the foldedposition of the fin, which is indicated in the drawing with a brokenline 66. The fin 46 can pivot between its folded position 66 and itsdeployed position in the direction of the arrow C in FIG. 9 . When thefin 46 is in its folded position 66, the tip 54 of the fin is disclosedcloser to the external surface 44 of the drainage layer 22 than when thefin is in its deployed position. A flank 68 of the fin is disposedproximate the external surface 44 when the fin is in its foldedposition. The ability of the fin 46 to fold or pivot in this way canfacilitate fitting of the filter element assembly 10 in its filterhousing, for example if access to the housing is restricted, such as ina tight or confined space, or if the housing opening 5 is small comparedto the filter element assembly 10 with the fin deployed.

As can best be appreciated from FIGS. 5 to 7 , the pivot pins 58 and 60are aligned along the longitudinal axis 56 of the pin 46, so that thefin pivots about its longitudinal axis when it is moved between itsfolded and deployed positions. The portion of the fin 46 defining thebase 52 extends a certain distance away from the longitudinal axis 56,so that the base 52 presses into the external surface 44 of the drainagelayer 22 to compress it, when the fin is pivoted to its deployedposition. Shaping the base 58 so that it is rounded as discussed abovehelps to prevent damage to the drainage layer 22 as the fin 46 pivotsbetween its different positions.

Fitting of the fin 46 to the filter element 12 is shown in FIG. 10 . Thefin 46 is typically of a polymeric material and may be resilientlydeformable for fitting to the filter element 12. The fin 46 may befitted by locating one of the pivot pins 58 and 60 in its respectivemounting socket 62 or 64 on the filter element 12. This requires thatthe fin 46 be disposed at an angle relative to the filter element 12, sothat its longitudinal axis 56 is transverse to the filter element axis42. The fin 46 can then be moved to a position in which the other one ofthe pivot pins 58 and 60 is proximate its mounting socket 62 or 64, andthe fin resiliently deformed to a certain extent in order to snap thepivot pin into its socket. This may be achieved by deforming the fin 46along its length, for example by causing it to adopt a curved shape,and/or the pin itself may be resiliently deformable so that it can passinto the socket. To facilitate fitting of the fin 46, the sockets 62 and64 on the end caps 24 and 26 may comprise radially outer lips 70 and 72forming outer wall portions of the sockets, over which the pivot pins 58and 60 can pass in order to be received in the sockets.

Although the fin 46 can be fitted to the filter element 12 by locatingthe fin at a transverse angle relative to the filter element, thesockets 62 and 64 on the end caps 24 and 26, and in particular theirlips 70 and 72, may be dimensioned so that the fin 46 can bepress-fitted to both sockets at the same time. This is shown in FIG. 10and can be achieved by bringing the fin 46 adjacent to the filterelement 12 with the fin axis 56 substantially parallel to the filterelement axis 42. The pivot pins 58 and 60 can then be press fitted intothe sockets, passing over the lips 70 and 72, this involving a smalldeformation of the fin 46 to adopt a curved shape, and/or deformation ofthe pivot pins 58 and 60, as discussed above.

The fin 46 will typically be located in its folded position duringinstallation of the filter element assembly 10 in a filter housing.Following location of the filter element assembly 10 in the housing withthe fin disposed at the bottom of the element (considered in acircumferential sense and viewing along the assembly), the fin 46 can bemanually rotated towards its deployed position, in which a transverseaxis 74 of the fin (FIG. 6 ) is disposed substantially on a radius ofthe filter element 12, which radius intersects with its longitudinalaxis 42.

As discussed above, the drainage promoter fin 46 may be of a polymericmaterial, and may be moulded, for example injection moulded. Suitablematerials may include Nylon, ABS (Acrylonitrile Butadiene Styrene),Polypropylene and Acetal (POM, PolyOxyMethylene). Constructing the fin46 from such materials may provide it with sufficient resilience/elasticdeformability for it to be fitted to the filter element 12. Othermaterials and manufacturing techniques may however be suitable,including die casting using an aluminium or zinc alloy, for example.

In the illustrated embodiment, the fin 46 includes pivot pins 58 and 60,and pivot mounts 62 and 64 are provided on the filter element 12. Itwill be understood however that this arrangement may be reversed so thatthe fin 46 is provided with mounts, and the filter element with pivotpins. Equally, the fin 46 may be provided with one pivot pin and onepivot mount, for engaging a corresponding mount and pin on the filterelement 12.

As discussed above, the drainage promoter 14 can readily be fitted tothe filter element 12 and facilitates drainage of liquid contaminantsfrom the gas stream flowing through the filter. The drainage promoterfin 46 is fitted to the end caps 24 and 26 of the filter element 12,which must carry appropriate fittings such as the pivot sockets 62 and64. Dedicated end caps will therefore need to be manufactured, althoughit is conceivable that existing filter elements could be modified bymounting additional structure on its end caps, providing mountings forthe connection features on the fin 46.

Turning now to FIG. 11 , there is shown a front view of a filter elementassembly in accordance with another embodiment of the presentdisclosure, the filter element assembly indicated generally by referencenumeral 10 a. The filter element assembly 10 a comprises a filterelement 12 a and a drainage promoter 14 a. Like components of the filterelement assembly 10 a with the filter element 10 shown in FIGS. 1 to 10share the same reference numerals, with the addition of the suffix “a”.

The filter element 12 a is of substantially the same construction as thefilter element 12 shown in FIGS. 1 to 11 and described above.Accordingly, details of the construction and operation of the filterelement 10 a will not be described again in detail, reference insteadbeing made to the discussion of the filter element 12 forming part ofthe filter element assembly 10 described above. Only substantialdifferences between the filter element assembly 10 a and the assembly 10will be described herein. In addition, the filter element assembly 10 acan be located in a housing 4 of a filter 2 in a horizontal orientationin the same way as the filter element assembly 10. Reference willtherefore be made to the discussion above concerning the way in whichthe filter element assembly 10 a is located in a filter housing, and theway in which it operates during use.

The filter element assembly 10 a is also shown in the end views of FIGS.12 and 13 , taken in the direction of the arrows A and B respectively inFIG. 11 . FIG. 14 is a perspective view, and FIG. 15 a longitudinalcross-sectional view of the filter element assembly 10 a, both drawn toa smaller scale.

In this embodiment, the drainage promoter 14 a again comprises a fin 46a which is releasably connectable to the filter element 12 a. The fin 46a is pivotable relative to the filter element 12 a for connecting it tothe element, the fin being shown in a connected position in FIGS. 11 to15 , and in a disconnected position in the side view of FIG. 16 , duringfitting of the fin to the filter element. The fin 46 a is also shownseparately in the front, end and perspective views of FIGS. 17, 18 and19 , the end view being taken in the direction of the arrow D in FIG. 17. The fin 46 a is drawn to the same scale in FIGS. 17 and 19 as it is inFIG. 11 but is shown in a different orientation.

The filter element assembly 10 a of FIGS. 11 to 19 differs from thefilter element assembly 10 largely in relation to the way in which thefin 46 a is connected to the filter element 12 a. To this end, both thefilter element 12 a, and the fin 46 a, include connection features whichare different to those of the respective filter element 12, and fin 46.

In this embodiment, a pivoting connection is provided between the fin 46a and the filter element 12 a which facilitates fitting of the fin tothe filter element. The fin 46 a has a first axial end 48 a and a secondaxial end 50 a. A first connection feature 58 a is provided at the firstaxial end 48 a, which is a male connection feature in the form of apivot pin. The male connection feature 58 a in fact comprises first andsecond pivot pin portions 76 and 78, which are generally cylindrical andhave rounded heads. The pivot pin portions 76 and 78 are aligned along atransverse axis 80, which is disposed substantially perpendicular to alongitudinal axis 56 a of the fin 46 a. The first pivot pin portion 76extends in a first lateral direction away from the longitudinal axis 56a, and the second pivot pin portion 78 in a second lateral direction.

The filter element end cap 24 a comprises a first connection feature 62a in the form of a pivot socket or mount, which is a female feature thatis shaped to receive the male connection feature defined by the pivotpin portions 76 and 78 on the fin 46 a. The female pivot mount 62 a onthe first end cap 24 a is best shown in the enlarged perspective detailview of FIG. 20 , as well as the end views of FIGS. 12 and 13 . Theconnection socket 62 a includes a channel 82 which is shaped to receivethe pivot pin portions 76 and 78, the channel being defined by a pair ofcurved arms 84 which extend from an outer perimeter 86 of the first endcap 24 a. A slot 88 is defined between ends of the two arms 84, which isshaped to receive the fin 46 and communicates with the channel 82. Thechannel 82 has a closed end 90 (FIG. 20 ), which defines a detent forthe pivot pin portions 76 and 78.

The fin 46 a is connected to the filter element 12 a by aligning thepivot pin portions 76 and 78 with the channel 82, as shown in FIG. 13 .The pivot pin portions 76 and 78 can then be translated along thechannel 82 until they come to rest at the closed end 90. The fin 46 a isthen in the position shown in FIG. 16 and can be pivoted about thetransverse axis 80 of the pivot pin portions 76 and 78, by moving thesecond axial end 50 a of the fin 46 a in the direction of the arrow F inFIG. 16 . The fin 46 a can then be secured to the second end cap 26 a atits second axial end 50 a, to secure the fin to the filter element 12 a.

Referring to FIG. 21 , which is an enlarged detail view of theconnection between the fin 46 a and the second end cap 26 a, the fincomprises a second connection feature 60 a, which in this embodiment isa latch feature that provides a latching engagement with the second endcap 26 a. The second end cap 26 a comprises a second connection feature64 a, and the latch feature 60 a on the fin 46 a engages the latchfeature 64 a on the end cap 26 a to secure the fin 46 a to the filterelement.

In the illustrated embodiment, the latch feature 60 a on the fin 46 acomprises a resiliently deformable latch arm 92 having a latch tooth 94.The latch feature 64 a on the end cap 26 a comprises a recess 96 whichthe latch tooth 94 of the latch arm 92 can engage in order to secure thefin 46 a to the end cap 26 a. A plurality of such recesses 96 may beprovided in the end cap 26 a, as shown in the end view of FIG. 13 . Thismay facilitate orientation of the end caps 24 a and 26 a duringmanufacture of the filter element 12 a, so that the connection features62 a and 64 a can be aligned for receiving the fin connection features58 a and 60 a.

When the fin 46 a is pivoted from its disconnected position of FIG. 16to its connected position of FIG. 21 , the latch arm 92 comes in tocontact with a chamfered surface 98 on the end cap 26 a. The latch tooth94 is similarly chamfered such that application of force to the fin 46 ain the direction F causes the latch arm 92 to deform, so that the latchtooth 94 can pass along the chamfered surface and over an end surface ofthe end cap 26 a, before latching into the recess 96 as shown in FIG. 21. The fin 46 a is then connected to the filter element 12 a.

The fin 46 a also includes a recess 100 at its second axial end 50 a,the recess being shaped to receive an outer peripheral portion 102 ofthe end cap 26 a. When the peripheral portion 102 is located in therecess 100, the fin 46 a is securely connected to the end cap 26 a,constrained between end faces of the recess. A further resilient latchtooth 104 on the fin 46 a snaps over an inner peripheral surface 106 ofthe end cap 26 a, to provide an additional restraint against separationof the fin 46 a from the filter element 12 a. Engagement of the secondaxial end 50 a of the fin 46 a to the end cap 26 a also acts to maintainengagement between the first axial end 48 a of the fin and the first endcap 24 a, because it prevents movement of the pivot pin portions 76 and78 out of the channel 82 defined between the arms 84. When fitted to thefilter element 12 a, the fin 46 a extends over the second end cap 46 a,and partly over the first end cap 24 a. A portion of the fin 46 aincluding its base 52 a is disposed between the end caps 24 a and 26 aand spans the distance between the end caps.

It will be understood that the orientation of the fin 46 a relative tothe filter element 12 a may be reversed, with the pivoting connectionprovided at the second end cap 26 a, and the latching connection at thefirst end cap 24 a.

Turning now to FIG. 22 , there is shown a front view of a filter elementassembly in accordance with another embodiment of the presentdisclosure, the filter element assembly indicated generally by referencenumeral 10 b. The filter element assembly 10 b comprises a filterelement 12 b and a drainage promoter 14 b. Like components of the filterelement assembly 10 b with the filter element 10 shown in FIGS. 1 to 10share the same reference numerals, with the addition of the suffix “b”.

The filter element 12 b is of substantially the same construction as thefilter element 12 shown in FIGS. 1 to 11 and described above.Accordingly, details of the construction and operation of the filterelement 10 b will not be described again in detail, reference insteadbeing made to the discussion of the filter element 12 forming part ofthe filter element assembly 10 described above. Only substantialdifferences between the filter element assembly 10 b and the assembly 10will be described herein. In addition, the filter element assembly 10 bcan be located in a housing 4 of a filter 2 in a horizontal orientationin the same way as the filter element assembly 10. Reference willtherefore be made to the discussion above concerning the way in whichthe filter element assembly 10 b is located in a filter housing 4, andthe way in which it operates during use.

The filter element assembly 10 b is also shown in the end views of FIGS.23 and 24 , taken in the direction of the arrows A and B respectively inFIG. 22 . FIG. 25 is a longitudinal cross-sectional view of the filterelement assembly 10 b, and FIG. 26 is a perspective view of theassembly, showing a fin 46 b of its drainage promoter 14 b prior toconnection to the filter element 12 b. The fin 46 b is shown in itsconnected state in FIGS. 22 and 25 , and in its disconnected state inFIG. 26 , as mentioned above. FIGS. 26A, B and C are front views of thefilter element assembly 10 b showing successive steps in connection ofthe fin 46 b to the filter element 12 b.

In this embodiment, a sliding connection is provided between the fin 46b and the filter element 12 b, the sliding connection being defined byconnection features of the fin and the filter element. The connectionfeatures on the fin are shown in more detail in the enlarged front andend views of FIGS. 27 and 28 , and the perspective view of FIG. 29 , theend view taken in the direction of the arrow D in FIG. 27 . The fin 46 bis translatable relative to the filter element 12 b between itsdisconnected position and its connected position. The fin 46 b has afirst axial end 48 b and a second axial end 50 b. A first connectionfeature 58 b is provided at the first axial end 48 b, and a secondconnection feature 60 b at the second axial end 50 b. The filter element12 b, in particular first and second end caps 24 b and 26 b of thefilter element, define corresponding connection features 62 b and 64 b,which cooperate with the respective first and second connection features58 b and 60 b on the fin 46 b, so that the fin can be connected to thefilter element end caps.

The second connection feature 60 b on the fin 46 b takes the form of aprotrusion or projection which defines a key, and which takes the formof an elongate finger. The second connection feature 64 b defined by thesecond end cap 26 b defines a keyway in the form of a channel which isshaped to receive the key 60 b of the fin 46 b in a sliding fit. The key60 b has to be aligned with the keyway 64 b in order for the features tobe connected. This is best shown in the end view of FIG. 24 .

The first connection feature 58 b on the fin 46 b similarly takes theform of a protrusion or projection defining a key. The first connectionfeature 62 b defined by the first end cap 24 b defines a keyway whichsimilarly receives the key 58 b in a sliding fit. Once again, the key 58b and the keyway 62 b must be aligned for connection of the features. Arestraint in the form of a shoulder 108 on the fin 46 b proximate thekey 60 b acts to resist further translation of the fin relative to thefilter element 12 b, once the fin has been translated a sufficientdistance relative to the filter element and adopted its connectedposition.

The key 58 b defined by the fin 46 b comprises key portions 110 and 112which are aligned along a transverse axis 80 b (FIG. 28 ) of the fin,the key portion 110 extending in a first lateral direction away from thefin, and the second key portion 112 in a second, opposite lateraldirection. The key portions 110 and 112 are shaped to engage within achannel 114 of the keyway 58 b on the first end cap 24 b, which isdefined by a pair of arms 116 and 118. The channel 114 tapers in adirection radially outwardly of the filter element 12 b and the keyportions 110 and 112 have a corresponding taper. This provides secureengagement of the key portions 110 and 112 within the channel 114 andacts to resist radial separation of the fin 46 b from the first end cap24 b when connected. Latch teeth 120, 122 on the respective arms 116 and118 engage on radially outer ledges 124, 126 of the respective keyportions 110, 112 to restrain them in the channel 114.

The keyway 64 b defined by the second end cap 26 b is similarly tapered,as is the key 60 b defined by the fin 46 b. This acts to restrain thekey 60 b within the keyway 64 b once the fin 46 b has been connected tothe filter element 12 b. The key 60 b also has a tapered leading end 128which assists alignment with the keyway 64 b during connection of thefin 46 b. The leading end 128 defines a latch tooth 130 which can engagein a circumferential recess 132 (FIG. 25 ) defined on a lower end of thesecond end cap 26 b. This acts to resist sliding movement of the fin 46b away from its connected position.

The keyways 62 b and 64 b on the end caps 24 b and 26 b, and the keys 58b and 60 b defined by the fin 46 b, must be aligned along an axis whichis parallel to a longitudinal access 42 b of the filter element 12 b inorder for connection of the fin to the element. The alignment axis isshown in the perspective view of FIG. 26 and given the reference numeral134. In use, and once the fin 46 b has been connected to the filterelement 12 b, a longitudinal axis 56 b of the fin 46 b resides on thealignment axis 134.

Fitting of the fin 46 b to the filter element 12 b is shown in the viewsof FIGS. 26A to C. As can be seen from FIG. 26A, a base 52 b of the fin46 b has an axial length which is slightly smaller than an axial lengthL₁ of the drainage layer 22 b disposed between the filter end caps 24 band 26 b. This allows the base 52 b to be inserted between the end caps24 b and 26 b, in contact with the drainage layer 22 b. This is shown inFIG. 26B. The key 60 b is aligned with the keyway 64 b, and the key 58 bwith the keyway 62 b, along the axis 134. The base 52 b of the fin 46 bhas facing end surfaces, one of which is defined by the shoulder 108,and the other by a shoulder 136 (FIG. 29 ). The key portions 110 and 112of the key 58 b are spaced along a length of the fin 46 b from theshoulder 136, defining an area 138 which can receive the arms 116 and118 of the keyway 62 b, so that the fin 46 b can be located between theend caps 24 b and 26 b as shown in FIG. 26B. In this position, the key60 b is axially spaced from the keyway 64 b on the second end cap 26 b,and the key 58 b is axially spaced from the keyway 62 b on the first endcap 24 b.

With the keys and keyways aligned as discussed above, the fin 46 b canthen be translated in the direction of the arrow G in FIG. 26C. Thisadvances the key 60 b into the keyway 64 b, and the key 58 b into thekeyway 62 b, so that they are located in their respective positionsshown in FIG. 24 and FIG. 23 and described above. The latch tooth 130engages in the circumferential recess 132 on the second end cap 26 b,and a lip 140 adjacent the shoulder 108 on the fin 46 b engages over aninner peripheral surface 106 b (FIG. 25 ) of the second end cap 26 b.When the fin 46 b is connected to the filter element 12 b, there is asmall gap 142 between the shoulder 136 on the fin and the first end cap24 b. This gap enables fitting of the fin 46 b between the end caps 24 band 26 b, and the translational movement of the fin between itspositions of FIG. 28 and FIG. 29 .

As can best be seen from FIGS. 24 and 26 , the second end cap 26 b infact comprises a plurality of keyways 64 b, which are spaced around acircumference of the end cap. The provision of such a plurality ofkeyways 64 b can aid manufacture of the filter element 12 b. Inparticular and as discussed above, the filtration and drainage layers 20and 22 of the filter element 12 b, as well as other components such asthe perforated support tubes 30 b and 32 b, are potted in the end caps24 b and 26 b using a suitable adhesive. In order for the fin 46 b to befitted to the filter element 12 b, the keyway 62 b on the first end cap24 b must be aligned with a keyway 64 b on the second end cap 26 b.Providing the large number of keyways 64 b spaced around thecircumference of the second end cap 26 b can simplify alignment with thekeyway 62 b during assembly.

When fitted to the filter element 12 b, the fin 46 b extends along thesecond end cap 26 b, and partly over the first end cap 24 b. A portionof the fin 46 a including its base 52 a is disposed between the end caps24 a and 26 a and spans a majority of the distance between the end caps.

Turning now to FIG. 30 , there is shown a front view of a filter elementassembly in accordance with another embodiment of the presentdisclosure, the filter element assembly indicated generally by referencenumeral 10 c. The filter element assembly 10 c comprises a filterelement 12 c and a drainage promoter 14 c. Like components of the filterelement assembly 10 c with the filter element assembly 10 shown in FIGS.1 to 10 share the same reference numerals, with the addition of thesuffix “c”.

The filter element 12 c and the drainage promoter 14 c are in fact ofvery similar construction to the filter element 12 b and the drainagepromoter 14 b of the filter element assembly 10 b shown in FIGS. 22 to29 and described above. In particular, the drainage promoter 14 ccomprises a fin 46 c which is connected to the filter element 12 c in asliding connection, in the same way as the fin 46 b is fitted to thefilter element 12 b. Reference is therefore made to the discussion ofFIGS. 22 to 29 concerning the way in which the fin 46 c is fitted to thefilter element 12 c.

The drainage promoter 14 c is shown separately, disconnected from thefilter element 12 c, in the front, end and perspective views of FIGS.31, 32 and 33 . The drainage promoter fin 46 c differs from the fin 46 bin that it comprises a plurality of drainage elements 144 to 162, eachof which is coupled to the fin 46 c and extends in a direction away fromthe fin. The drainage elements 144 to 162 each take the form of afinger, rib, arm or the like, and are typically moulded integrally withthe fin 46 c. It will be understood however that the drainage elements144 to 162 may be manufactured separately and subsequently connected tothe fin 46 c. The drainage elements 144 to 162 each extend in adirection around an outer surface of a drainage layer 22 c of the filterelement 12 c, as shown in FIG. 30 , and act to compress the drainagelayer along their lengths, to further promote the drainage of liquidfrom the drainage layer and on to the fin 46 c.

A first row or array of drainage elements 164 comprises drainageelements 144, 148, 152, 156 and 160, which each extend from the fin 46 cin a first lateral direction, from a first flank 165 of the fin. Asecond row or array 166 comprises the drainage elements 146, 150, 154,158 and 162 which each extend from the fin 46 c in a second lateraldirection, from a second flank 167 of the fin. The drainage elements inthe arrays 164 and 166 each extend partway around a circumference of anexternal surface 44 c of the drainage layer 22 c when the drainagepromoter 14 c is fitted to the filter element 12 c. The drainageelements 144 to 162 in the two rows 164 and 166 together act to promotedrainage of liquid from a wet band or zone 170, which can form duringuse of the filter element 12 c. Accordingly, the drainage element needonly extend around part of the circumference of the drainage layer 22 cin order to provide the enhanced drainage effect.

The drainage elements 144 to 162 are each disposed transverse to alongitudinal axis 56 c of the fin and are suitably disposedsubstantially perpendicular to the fin axis, as can be seen in FIG. 31 .It will be understood however that the drainage elements 144 to 162 maybe oriented so that they are transverse to the fin axis 56 c but atnon-perpendicular angles. The drainage elements 144 to 162 are eachcurved, having inner surfaces which have a curvature that substantiallymatches a curvature of the external surface 44 c of the drainage layer22 c, an inner surface of drainage element 144 being shown in FIG. 33and given the reference numeral 172.

The drainage elements 144 to 162 each have a base at which they arecoupled to the fin, a base 174 of the drainage element 146 being shownin FIG. 33 . The drainage elements 144 to 162 each taper in a directionfrom their base towards a respective tip, the tip 176 of drainageelement 146 being shown in FIG. 33 . As can best be seen from FIG. 31 ,a width of each drainage element W₁ at its base (shown for the drainageelement 146 in FIG. 31 ) reduces in a direction towards its tip, to awidth W₂. An effective depth D₁ of the drainage element 144 to 162 alsoreduces in a direction from its base 174 towards its tip 176, as againshown in FIG. 31 . The reduced depth at the tip 176 can be appreciatedfrom the perspective view of FIG. 33 . Providing drainage elements 144to 162 which taper in width and/or depth may help to promote the flow ofliquid along the drainage elements and on to the fins 46 c forsubsequent discharge, during use of the drainage promoter 14 c.

The drainage elements in the first row 164 are axially staggered along alength of the fin 46 c relative to the drainage elements in the secondrow 166. This can best be seen from FIG. 31 . Staggering the drainageelements in the first row 164 relative to the second row 166 can help toimprove drainage of liquid from the drainage layer 22 c in the wet band170. It will be understood however that the drainage elements in thefirst and second rows 164 and 166 may be axially aligned, for example byarranging the elements in pairs at common axial positions. For example,and viewing FIG. 31 , the drainage elements 144 and 146 may be arrangedat a common axial position, and so aligned along a transverse axis ofthe fin 46 c.

Whilst the drainage elements 144 to 162 have been shown on a fin 46 cwhich is a sliding connection to its filter element 12 c in the fashionof the fin 46 b to the element 12 b, it will be understood that similarsuch drainage elements may be provided on any of the other drainagepromoters/fins disclosed in this document. By way of non-limitingexample therefore, similar such drainage elements may be provided on thefin 46 of FIG. 1 , and on the fin 46 a of FIG. 11 .

Turning now to FIG. 34 , there is shown a front view of a filter elementassembly in accordance with another embodiment of the presentdisclosure, the filter element assembly indicated generally by referencenumeral 10 d. The filter element assembly 10 d comprises a filterelement 12 d and a drainage promoter 14 d. Like components of the filterelement assembly 10 d with the filter element 10 shown in FIGS. 1 to 10share the reference numerals, with the addition of the suffix “d”.

The filter element 10 d is of substantially the same construction as thefilter element 12 shown in FIGS. 1 to 11 and described above.Accordingly, details of the construction and operation of the filterelement 10 d will not be described again in detail, reference insteadbeing made to the discussion of the filter element 12 forming part ofthe filter element assembly 10 described above. Any substantialdifferences between the filter element assembly 10 d and the assembly 10will be described herein. In addition, the filter element assembly 10 dcan be located in the housing 4 of a filter 2 in a horizontalorientation in the same way as the filter element assembly 10. Referencewill therefore be made to the discussion above concerning the way inwhich the filter element assembly 10 d is located in a filter housing 4,and the way in which it operates during use.

The filter element assembly 10 d is also shown in the end views of FIGS.35 and 36 , taken in the direction of the arrows A and B respectively inFIG. 34 . FIG. 37 is a perspective view and FIG. 38 a longitudinalcross-sectional view of the filter element assembly 10 d, both drawn toa smaller scale.

In this embodiment, the drainage promoter 14 d can be connected to adrainage layer 22 d of the filter element 12 d, rather than to first andsecond end caps 24 d and 26 d of the filter element 12 d, in the waythat the previously described drainage promoters are connected to theirrespective filter elements. The drainage promoter 14 d is connected tothe filter element 12 d at a location between first and second end caps24 d and 26 d of the filter element. A fin 46 d of the drainage promoter14 d comprises connection features which serve for connecting the findirectly to the drainage layer 22 d. In this case, the connectionfeatures take the form of resilient elements which are similar to thedrainage elements 144 to 162 forming part of the drainage promoter 14 cdiscussed above.

The drainage promoter 14 d is shown separately in the front, end andperspective views of FIGS. 39, 40 and 41 . A first array 164 d ofconnection elements is provided, comprising connection elements 144 d,148 d, 152 d, 156 d and 160 d. A second row or array 166 d comprisesconnection elements 146 d, 150 d, 154 d, 158 d and 162 d. The connectionelements 144 d to 162 d are of similar construction to the drainageelements 146 to 162 described above, and can also provide a drainagefunction, serving to enhance the flow of liquid from the drainage layer22 to the fin 46 d. However, a primary function of the connectionelements 144 d to 162 d in this embodiment is to connect the fin 46 d tothe drainage layer 22 d, and so to the filter element 12 d.

The connection elements 144 d to 162 d each have a shape which issubstantially similar to the drainage elements 144 to 162, tapering froma base 174 d towards a tip 176 d, which is shown for the connectionelement 144 d in the end view of FIG. 40 . In this embodiment however,the drainage elements 144 d to 162 d are arranged to impart a clampingforce on the drainage layer 22 d, for connecting the drainage promoter14 d to the filter element 12 d. Specifically, the connection elementsare arranged in pairs, axially adjacent connection elements (taken in adirection along a length of the fin 46 d) acting together to provide theclamping force. A clamping force is therefore exerted between theconnection elements 144 d and 146 d, as well as between successive pairsof connection elements along the length of the fin 46 d. Thus, aclamping force is along exerted between the connection elements 146 dand 148 d, the connection elements 148 d and 150 d and so on. This isachieved by providing the connection elements as resilient arms, fingersor the like in a similar fashion to the drainage elements 144 to 162described above.

In order to provide the clamping force, the connection elements 144 d to162 d each extend from the fin 46 d around a circumference of the filterelement 12 d to an over-centre position, relative to a centrallongitudinal axis 56 d of the filter element 12 d. A location of thecentral axis 56 d, and the over-centre positioning of the connectionelements 144 d to 162 d, is shown in the end view of FIG. 40 . As can beseen, the pair of connection features 144 d and 146 d together encompassmore than half of a circumference of the circular section drainage layer22 d, and so the filter element 12 d. Effectively, the connectionelements 144 d to 162 d together describe a generally cylindricalpassage or opening 178 which is shaped to receive the filter element 12d. A space is defined between the ends 176 of the connection elements144 d to 162 d, the space indicated generally by reference numeral 180in FIG. 20 . A dimension W₂ of the space 180 is smaller than a diameterof the filter element 12 d at its drainage layer 22 d. This serves toprovide the clamping force.

The drainage promoter 14 c described above is typically moulded as aunitary or one-piece component, comprising its fin 46 c and drainagefeatures 144 to 162. The drainage promoter 14 d can similarly beconstructed as a unitary or one-piece structure, which would thenrequire a push-fit of the drainage promoter to the drainage layer 22 d.This would require that the space 180 defined between the tips 176 ofthe connection features 144 d to 162 d be opened up to pass around thedrainage layer 22 d, over its diameter to the over-centre position shownin FIG. 40 .

It may therefore be preferable to construct the drainage promoter 14 das a two-piece structure, to facilitate fitting of the drainage promoterto the filter element 12 d. This is best shown in the end view of thedrainage promoter 14 d in FIG. 42B, and the end view of the assembly inFIG. 42A, showing fitting of the drainage promoter to the filter element14 d. Referring to FIG. 42B, first piece 182 of the drainage promoter 14d comprises a first part 184 of its fin 46 d and the first row 164 d ofconnection features. A second piece 186 comprises a second part 188 ofthe fin 46 d and the second row 166 d of connection features. The firstpart 184 of the fin 46 d defines a first flank 165 d of the fin and aplanar inner mating surface 190. The second part 188 of the fin 46 dcomprises a second flank 167 d of the fin and a planar inner matingsurface 192. The planar mating surface 190 is shown in thecross-sectional view of FIG. 38 and carries a number of matingprotrusions 194 and mating apertures 196, the protrusions engaging incorresponding apertures (not shown) on the mating surface 192 and theapertures receiving corresponding mating protrusions 198 (one shown) onthe mating surface 192. Engagement between the respective matingprotrusions and apertures on the planar surfaces 190 and 192 serves forconnecting the first and second pieces 182 and 186 of the fin togetheras shown in FIG. 40 . The first fin piece 182 is typically fitted to thedrainage layer 22 d of the filter element 12 d as shown in FIG. 42A, andthen the other fin piece 186 is connected to the first fin piece, sothat the connection features 144 d to 162 d clamp the drainage layer 22d.

When fitted to the filter element 12 d, the fin 46 d is disposed betweenthe end caps 24 d and 26 d and spans a majority of the distance betweenthe end caps.

Turning now to FIG. 43 , there is shown a front view of a filter elementassembly in accordance with another embodiment of the presentdisclosure, the filter element assembly indicated generally by referencenumeral 10 e. The filter element assembly 10 e comprises a filterelement 12 e and a drainage promoter 14 e. Like components of the filterelement assembly 10 e with the filter element assembly 10 shown in FIGS.1 to 10 share the same reference numerals, with the addition of thesuffix “e”.

The filter element 12 e is of substantially the same construction as thefilter element 12 shown in FIGS. 1 to 11 and described above.Accordingly, details of the construction and operation of the filterelement 10 e will not be described again in detail, reference insteadbeing made to the discussion of the filter element 12 forming part ofthe filter element assembly 10 described above. Any substantialdifferences between the filter element assembly 10 e and the assembly 10will be described herein. In addition, the filter element assembly 10 ecan be located in a housing 4 of a filter 2 in a horizontal orientationin the same way as the filter element assembly 10. Reference willtherefore be made to the discussion above concerning the way in whichthe filter element assembly 10 e is located in a filter housing 4, andthe way in which it operates during use.

The filter element assembly 10 e is also shown in the end views of FIGS.44 and 45 , taken in the direction of the arrows A and B respectively inFIG. 43 . In this embodiment, the drainage promoter 14 e can beconnected to the filter element 12 e at a location between first andsecond end caps 24 e and 26 e of the filter element. The drainagepromoter 14 e can be connected to a drainage layer 22 e, in a similarfashion to the drainage promoter 14 d discussed above.

The drainage promoter 14 e comprises a fin 46 e and first and secondconnection elements 200 and 202 which can engage the drainage layer 22e, to connect the fin to the filter element. In the illustratedembodiment, the connection components 200 and 202 are spaced spart alonga length of the fin 46 e and are suitably provided at respective firstand second axial ends 48 e and 50 e of the fin 46 e. It will beunderstood however that the connection components 200 and 202 may beprovided at alternative locations on the fin 46 e, and/or that more thantwo connection components, or conceivably only a single connectioncomponent, may be provided.

The connection components 200 and 202 each take the form of a strap ortie which extends from the fin 46 e and around a circumference of thedrainage layer 22 e. The drainage promoter 14 e is shown separately inthe front, end and perspective views of FIGS. 46, 47 and 48 , which aredrawn to a smaller scale, FIG. 47 viewing in the direction of the arrowD in FIG. 46 .

The first strap 200 comprises a first strap portion 204 which extends ina first direction away from the fin 46 e and around part of a perimeterof the drainage layer 22 e, and a second strap portion 206 which extendsin a second opposite direction away from the fin and around a furtherpart of the perimeter of the drainage layer. The first and second strapportions 204 and 206 can be coupled together to connect the fin 46 e tothe filter element 12 e. To this end, the strap portions 204 and 206comprise respective connection features 205 and 207 which serve forcoupling the portions together.

The first strap portion 204 comprises a female connection feature in theform of an aperture 205 formed in a stepped end section 209. The secondstrap portion 206 comprises a male connection feature in the form of aprotrusion such as a button 207, which can be located within theaperture 205 in a press-fit, to secure the strap portions 204 and 206together. The button 207 may include an enlarged head and may beresiliently deformable for passing through the aperture 205 and securingthe strap portions 204 and 206 together. It will be understood that thisrepresents just one option for the way in which the strap portions 204and 206 can be coupled together. Alternatives can be envisaged,including a zip-tie type structure, a separate mechanical connection, orthe use of an adhesive. The second strap 202 comprises similar suchfirst and second strap portions 208 and 210 which also compriseconnection features in the form of an aperture 212 and a button 214.

The straps 200 and 202 extend from the fin 46 e to encompass the entirecircumference of the drainage layer 22 e, when their respective strapportions 204/206 and 208/210 are coupled together. In a variationhowever, a strap may be provided comprising a single portion whichsubstantially encircles the drainage layer 22 e, the strap being coupledat one end to the fin 46 e and having a free end which can be connectedto the fin after encircling the drainage layer. In a further variation,one or more straps may be provided separately, and may be connectable tothe fin 46 e to secure it to the filter element 12 e, for example bypassing through a locating aperture in the fin and around the drainagelayer (or in an alternative, around an end cap).

FIGS. 49 and 50 are front and end views of the filter element assembly10 e shown during fitting of the drainage promoter 14 e to the filterelement 12 b, drawn to a smaller scale. As shown in these drawings, thedrainage promoter is introduced to the filter element 12 e so that thefin 46 e is positioned adjacent to the drainage layer 22 e and locatedbetween the end caps 24 e and 26 e. The first strap portions 204 and 208pass away from the fin 46 e on one side of the fin, and the second strapportions 206 and 210 pass away from the other side of the fin. The strapportions 204 and 206 can then be brought together to encircle thedrainage layer 22 e, by bringing ends of the strap portions together inthe direction of the arrows E and F shown in FIG. 50 . The stepped endportion 209 on the first strap portion 204 can be located so that itpasses over the button 207 on the second strap portion 206, and thebutton press-fitted through the aperture 205 to connect the two strapportions together. A similar procedure can then be followed for thestrap portions 208 and 210 of the second strap 202.

Engagement of the strap portions 204, 206 and 208, 210 exerts a clampingforce on the drainage layer 22 e, causing the fin 46 e to press into itsexternal surface 44 e, as shown in the longitudinal cross-sectional viewof FIG. 51 . The fitted drainage promoter 14 e therefore adopts theposition shown in the perspective view of FIG. 52 . The connectionstraps 200 and 202 can also act to compress the drainage layer 22 e, toprovide improved drainage, in a similar fashion to the drainage elementsdiscussed above.

When fitted to the filter element 12 e, the fin 46 e is disposed betweenthe end caps 24 e and 26 e and spans the distance between the end caps.

Drainage promoters of the type disclosed in this document which can beconnected to a drainage layer of a filter element (in particular thedrainage promoters 14 e and 14 d) may provide the advantage that theycan be connected to filter elements of a standard type, withoutnecessarily requiring any modification to be made to the structure ofthe filter element, in particular its end caps. These and other drainagepromoters disclosed in this document can provide the advantage that theycan be removed from the filter element and connected to a furtherelement, say in the situation where the filter element becomes cloggedduring use and requires replacement. This may provide material and costbenefits.

Various modifications may be made to the foregoing without departingfrom the spirit or scope of the present invention.

Numerous different embodiments of drainage promoters and filter elementsto which the disclosed drainage promoters can be fitted are disclosed inthis document. In further variations, the features of one or more of thedisclosed embodiments may be provided in combination. Thus, for example,combinations of sliding and pivoting connection features, and connectionfeatures involving connection to a drainage layer rather than end capsof a filter element, may be provided in combination in furtherembodiments.

In each embodiment of filter element assembly disclosed in thisdocument, either of the first and second end caps may comprise a portfor the entry of gas into the filter element. In relevant embodiments,the fin may be connected differently to end caps of the filter element,for example in the embodiment of FIG. 11 , the fin 46 a may be pivotallyconnected to the second end cap 26 a and may latch-fit to the first endcap 24 a.

Reference is generally made in this document to a filter elementcomprising a wall of a filtration medium which defines a hollow spacefor a gas stream to flow from the space through the wall to be filtered,and a drainage layer located outside the filtration layer in whichliquid separated from the gas stream can collect, as well as to adrainage promoter which compresses the drainage layer to promotedrainage of liquid which has collected in the drainage layer. Referencemay however be made generally to a fluid stream (which may notspecifically be a gas), and to the drainage of fluid (which may notspecifically be a liquid) which has collected in the drainage layer. Thefluid which is collected in the drainage layer may have been filteredfrom the fluid stream flowing through the wall of the filter element.The fluid stream may therefore comprise a first fluid and at least onefurther fluid, which further fluid may collect in the drainage layer.

1. A filter element assembly, comprising: a filter element for location in a housing of a filter, the filter element comprising a wall of a filtration medium which defines a hollow space, for a gas stream to flow from the space through the wall to be filtered, the filtration medium including a filtration layer, and a drainage layer located outside the filtration layer in which liquid separated from the gas stream can collect, and first and second end caps at opposite ends of the wall, one of the end caps including a port for a gas stream which communicates with the space within the wall; and a drainage promoter comprising a fin configured to be connected to the filter element so that, in use, it extends along the filter element substantially an entire distance between the first and second end caps and compresses the drainage layer along its length to promote drainage of liquid which has collected in the drainage layer, and wherein the fin comprises at least one connection feature for engaging the filter element, to connect the fin to the filter element.
 2. The filter element assembly as claimed in claim 1, in which the fin is elongate, having first and second axial ends, a base extending along a length of the fin between the ends, and a tip opposite the base and extending along the length of the fin, in which the tip defines a free edge of the fin and the base presses into the drainage layer during use.
 3. The filter element assembly as claimed in claim 2, in which the tip defines a discharge location from which liquid flowing from the drainage layer can be discharged from the fin, and in which the fin has a tapered shape in cross-section, tapering in a direction towards its tip.
 4. The filter element assembly as claimed in claim 1, in which the fin is configured to be connected to at least one of the first and second end caps, so that it can be secured to the filter element.
 5. The filter element assembly as claimed in claim 4, in which the fin is configured to be connected to both end caps so that it extends from one end cap to the other end cap.
 6. The filter element assembly as claimed in claim 1, in which the fin is configured to be releasably connected to at least one of the end caps.
 7. The filter element assembly as claimed in claim 1, in which the connection feature engages an end cap of the filter element.
 8. The filter element assembly as claimed in claim 7, in which the fin comprises a first connection feature for engaging one of the end caps, and a second connection feature for engaging the other one of the end caps, the first and second connection features being spaced apart along a length of the fin.
 9. The filter element assembly as claimed in claim 8, in which the fin comprises a first axial end and a second axial end, and the first and second connection features are provided at or near the respective first and second axial ends.
 10. The filter element assembly as claimed in claim 7, in which the filter element comprises at least one connection feature, which cooperates with the connection feature on the fin for connecting the fin to the element.
 11. The filter element assembly as claimed in claim 10, in which at least one of the end caps comprises the connection feature.
 12. The filter element assembly as claimed in claim 11, in which the first end cap comprises a first connection feature and the second end cap comprises a second connection feature, the first and second end cap connection features being configured to cooperate with respective first and second connection features of the fin, to connect the fin to the filter element.
 13. The filter element assembly as claimed in claim 10, in which: the connection feature of the fin is a male connection feature, and the connection feature of the filter element is a corresponding female connection feature; or the connection feature of the fin is a female connection feature, and the connection feature of the filter element is a corresponding male connection feature.
 14. The filter element assembly as claimed claim 1, comprising a pivoting connection between the fin and the filter element.
 15. The filter element assembly as claimed in claim 14, in which one of the fin and the filter element defines a connection feature in the form of a pivot pin, and the other one of the fin and the filter element defines a pivot mount shaped to receive the pivot pin, so that the fin can pivot relative to the filter element.
 16. The filter element assembly as claimed in claim 15, in which the pivot pin and the pivot mount are aligned along a longitudinal axis of the fin, so that the fin can pivot about its longitudinal axis between a folded position and a deployed position.
 17. The filter element assembly as claimed in claim 15, in which the fin comprises a pivot pin or a pivot mount at each of its ends, configured to engage a corresponding pivot mount or pivot pin of the filter element.
 18. The filter element assembly as claimed in claim 15, in which the pivot pin and the pivot mount are disposed on a pivot axis which is transverse to the longitudinal axis of the fin when the fin is connected to the filter element.
 19. The filter element assembly as claimed in claim 18, in which the fin comprises a first pivot pin portion extending in a first lateral direction away from the fin, and a second pivot pin portion extending in a second lateral direction away from the fin.
 20. The filter element assembly as claimed in claim 18, in which the fin is pivotable about the pivot axis between a disconnected position in which the fin is not connected the filter element, and a connected position in which the fin is connected to the filter element, and in which, in the connected position, the longitudinal axis of the fin is disposed substantially parallel to a longitudinal axis of the filter element.
 21. The filter element assembly as claimed in claim 18, in which the fin and the filter element define respective latch features, which cooperate to provide a latching engagement between the fin and the element.
 22. The filter element assembly as claimed in claim 21, in which the latch feature on the fin is spaced along a length of the fin from its pivot pin or pivot mount, and the latch feature on the filter element is provided on one of the end caps.
 23. The filter element assembly as claimed in claim 21, in which one of the latch features provided by the fin and the filter element is a resiliently deformable latch arm.
 24. The filter element assembly as claimed in claim 10, comprising a sliding connection between the fin and the filter element, the sliding connection defined by connection features of the fin and the filter element.
 25. The filter element assembly as claimed in claim 24, in which the fin is translatable relative to the filter element between a disconnected position in which it is not connected to the filter element, and a connected position in which it is connected to the filter element.
 26. The filter element assembly as claimed in claim 24, in which one of the fin and the filter element defines a connection feature in the form of a key, and the other one of the fin and the filter element defines a keyway shaped to receive the key in a sliding fit.
 27. The filter element assembly as claimed in claim 24, in which the first end cap comprises a first connection feature for engaging a corresponding first connection feature on the fin, the second end cap comprises a second connection feature for engaging a corresponding second connection feature on the fin, and in which the respective first connection features of the filter element and the fin, and the respective second connection features of the filter element and the fin, require to be aligned in order for the fin to be connected to the element.
 28. The filter element assembly as claimed in claim 24, in which at least one of the end caps comprises a plurality of connection features which are spaced around a perimeter of the end cap.
 29. The filter element assembly as claimed in claim 1, in which the fin is configured so that it is connected to the filter element in a press-fit between the end caps.
 30. The filter element assembly as claimed in claim 1, in which the drainage promoter comprises at least one drainage element which is coupled to the fin and extends in a direction away from the fin and around an outer surface of the drainage layer.
 31. The filter element assembly as claimed in claim 30, in which the drainage element extends part way around a perimeter of the outer surface and is disposed transverse to a longitudinal axis of the fin.
 32. The filter element assembly as claimed in claim 1, in which the at least one drainage element has a base at which it is coupled to the fin and extends away from the base to a tip which defines a free end, the at least one drainage element tapering in a direction from the base towards the tip.
 33. The filter element assembly as claimed in claim 30, in which, in use, at least one first drainage element extends from the fin around the outer surface of the drainage layer in a first direction around the perimeter of the filter element, and at least one second drainage element extends from the fin around the outer surface of the drainage layer in a second direction around the perimeter of the filter element.
 34. The filter element assembly as claimed in claim 33, in which the first and second drainage elements extend from respective first and second flanks of the fin.
 35. The filter element assembly as claimed in claim 33, in which, in use, the first and second drainage elements are configured to together impart a clamping force on the filter element, for connecting the drainage promoter to the element.
 36. The filter element assembly as claimed in claim 33, in which, in use, the drainage elements each extend around the perimeter of the filter element to an over-centre position, relative to a central axis of the filter element, so that the first and second drainage elements together encompass more than half of a circumference of the filter element.
 37. The filter element assembly as claimed in claim 33, in which the first and second drainage elements together describe a generally cylindrical passage between their inner surfaces, which passage is shaped to receive the filter element.
 38. The filter element assembly as claimed in claim 37, in which the passage has a central axis, and the drainage elements each extend, in use, to an over-centre position relative to the central axis.
 39. The filter element assembly as claimed in claim 33, in which a space is defined between a free end of the first drainage element and a free end of the axially adjacent second drainage element, and in which a dimension of the space, measured in a direction perpendicular to a longitudinal axis of the filter element, is smaller than a width of the filter element.
 40. The filter element assembly as claimed in claim 30, in which the drainage promoter comprises a first part defining a first part of the fin and at least one drainage element, and a second part defining a second part of the fin and at least one drainage element, and in which the first and second fin parts are adapted to be coupled together to form the drainage promoter.
 41. The filter element assembly as claimed in claim 1, in which the drainage promoter is configured to be connected to the filter element at a location between the first and second end caps.
 42. The filter element assembly as claimed in claim 41, in which the drainage promoter comprises at least one connecting component which is configured to engage the drainage layer, to connect the fin to the filter element.
 43. The filter element assembly as claimed in claim 42, in which the connecting component is a strap which extends, in use, from the fin and around at least part of a perimeter of the drainage layer.
 44. The filter element assembly as claimed in claim 43, in which the strap comprises a first strap portion extending, in use, in a first direction away from the fin and around part of a perimeter of the drainage layer, and a second strap portion extending in a second direction away from the fin and around part of a perimeter of the drainage layer, and in which the first and second strap portions are adapted to be coupled together to connect the fin to the filter element.
 45. A drainage promoter which can be connected to a filter element, the drainage promoter comprising: at least one fin which can be fitted to the filter element so that it extends along the filter element substantially an entire distance between first and second end caps of the filter element, to compress a drainage layer of the filter element along its length and promote drainage of liquid which has collected in the drainage layer; in which the fin comprises a first connection feature configured to engage the first end cap of the filter element, and a second connection feature configured to engage the second end cap of the filter element, for connecting the fin to the filter element.
 46. A drainage promoter which can be connected to a filter element, the drainage promoter comprising: at least one fin which can be fitted to the filter element so that it extends along the filter element substantially an entire distance between the first and second end caps, to compress a drainage layer of the filter element along its length and promote drainage of liquid which has collected in the drainage layer; and at least one connecting component configured to engage the drainage layer to connect the fin to the filter element.
 47. A drainage promoter which can be connected to a filter element, the drainage promoter comprising: at least one fin which can be fitted to the filter element so that it extends along the filter element substantially an entire distance between the first and second end caps, to compress a drainage layer of the filter element along its length and promote drainage of liquid which has collected in the drainage layer, the fin having first and second axial ends and a longitudinal axis extending along the fin between its axial ends; and at least one drainage element coupled to the fin and extending in a direction away from the fin, transverse to its longitudinal axis.
 48. A method of improving drainage of liquid from a drainage layer of an existing filter element, the method comprising fitting a drainage promoter according to claim 47 to the drainage layer of the filter element.
 49. A filter element for location in a housing of a filter, the filter element comprising: a wall of a filtration medium which defines a hollow space, for a fluid stream to flow from the space through the wall to be filtered, the filtration medium including a filtration layer, and a drainage layer located outside the filtration layer in which fluid separated from the fluid stream can collect; first and second end caps at opposite ends of the wall, one of the end caps including a port for a fluid stream which communicates with the space within the wall; and at least one connection feature configured to cooperate with a connection feature on a drainage promotor fin, for connecting the filter element to the drainage promotor fin.
 50. A filter element assembly, comprising: a filter element for location in a housing of a filter, the filter element comprising a wall of a filtration medium which defines a hollow space, for a gas stream to flow from the space through the wall to be filtered, the filtration medium including a filtration layer, and a drainage layer located in surrounding relation to the filtration layer in which liquid separated from the gas stream can collect, and first and second end caps at opposite ends of the wall, one of the end caps including a port for a gas stream which communicates with the hollow space within the wall; and a drainage promoter comprising a fin connected to the filter element so that, the drainage promoter extending along the filter element substantially an entire distance between the first and second end caps and compressing the drainage layer along its length to promote drainage of liquid which has collected in the drainage layer during use, and wherein the fin comprises at least one connection feature for engaging the filter element, to connect the fin to the filter element.
 51. The filter element assembly as claimed in claim 50, in which the first end cap comprises a first connection feature and the second end cap comprises a second connection feature, the first and second end cap connection features being configured to cooperate with respective first and second connection features of the fin, to connect the fin to the filter element.
 52. The filter element assembly as in claim 50, in which the first and second connection features of the first and second end caps are configured to releasably connect the fin to the filter element. 